Escapement mechanism.



- Patented Oct. 3|, I899. J. M. FAIRFIELD & E. H. DODGE.

ESCAPEMENT MECHANISM.

(Application med Mar. 4, 1899.\ (No Model.)

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Patented Oct. 3|, l899.

L t e e h s s t e e h s 2 E G D 0 M D S .m N H A m H 4 E Ea Dam m m E E m IMF. .r E m RPM I A w n 8 E M M d 0 M o m INVENTORS c/Ofin M lkir a'e Id WITNESSES Edwin Efl ATTORNEY UNITED STATES PATENT OFFICE.

JOHN M. FAIRFIELD'AND EDWIN I-I. DODGE, OF HARTFORD, CONNECTICUT, ASSIGNORS TO THE HARTFORD TYPEWRITER COMPANY, OF SAME PLACE.

ESCAPEMENT MECHANISM.

SPECIFICATION forming part of Letters Patent No. 635,957, dated October 31, 1899.

Application filed March t, 1899. Serial No. 707.716. (No model.)

T0 at whom it may concern.-

Be it known that we, JOHN M. FAIRFIELD and EDWIN I-I. DODGE, citizens of the United States, residing at Hartford, Hartford county, Connecticut, have invented certain new and useful Improvements in Escapement Mechanism, of which the following is a full, clear, and exact description.

Our invention relates to an escapement mechanism, and especially to one which may be employed in type-writers or other like machines.

In type-writing machines it is desirable that when the escapement mechanism releases the carriage the tension device shall move the carriage quickly along until the escapement mechanism stops it. In cases where the full force of the tension device is brought to bear upon the dogs, they, as well as the teeth of the rack or ratchet-wheel, must endure a severe shock when the carriage is stopped. On account of the short movement of the carriage in spacing the letters the teeth of the rack, when one is used, as 'well the dogs which work in it, are necessarily small and delicate, and this shock will often break them off. We provide an escapement mechanism which does away with the violence of this shock, and consequently is not so apt to break the teeth of the rack or the dogs, but will act as a cushioning means for the dogs. Furthermore, considerable friction is developed at this point because the dogs have to sustain the full thrust of the carriage movement, and this friction is directly transmitted to the key-action, thereby stiffening it to a very objectionable degree, and it will be observed that increasing the tension on the carriage to accommodate rapid operators results in harder finger action, which such operators have to overcome. Several other advantages of our construction will be apparent from an inspection of the drawings, showing the preferred embodiment of our invention, in which Figure 1 represents our invention in plan view. Fig. 2 represents an enlarged detail of the escapement mechanism in side elevation. Fig. 3 represents a sectional View of the same on the line 3 3 of Fig. 2. Fig. 4 represents a horizontal sectional View of Fig.

2 on the line 2 2. Fig. 5 represents a dia grammatic view of the connection from the key to the escapement.

In the above embodiment, A represents the frame of the type-writer, and A is a carriage movable relatively to the frame.

B are projections, in this embodiment formed by teeth of a rack B, carried by the carriage.

C is a portion of the frame, supporting, by the cone-screws D a shaft D, which carries a spirally-grooved wheel D, into which the teeth B of rack B project, so that when the carriage and rack are moved along in one direction or the other the spirally grooved Wheel D will be rotated thereby. E is a ratchet-wheel also carried on shaft D and rotated by the rotation of said wheelD'.

F is a detent for stopping and releasing the ratchet-wheel, and consequently the carriage pivoted in the frame, as shown. This detent is in this embodiment composed of a fixed dog Cr and a relatively movable one G. These dogs engage the ratchet-wheel E in the manner broadly common in this art. The detent F is rocked by the elbow-lever H, which is engaged by the rod I, connected with the key J, as shown in Fig. 5. a force uponsaid carriage to move it in one direction, such as a spring and band. When the key J is pressed downward, the elbow-lever H will rock the detent and release the ratchet-wheel E. This will release the carriage and the spring K will move it along in the direction of the arrow. The teeth B on the rack will strike against the right-hand sides of the spiral grooves, Fig. 2, and will rotate the wheel by the resultant of the pressure against the same. The wheel D is between the carriage and detent-that is, the wheel is rotated after the carriage is released and before it is stopped by the detent. When the detent releases the ratchet-wheel and allows the carriage to move, the inertia of the wheel D and the other rotating parts must be first overcome; but as these parts are comparatively very light and are mounted upon bearings which cause very little friction the result accomplished is practically entire freedom of the carriage in its forward movement until the dog acts upon a new toothin the K is a means to exert ratchet-wheel and checks the rotation. When this occurs, the pitch of the grooves on the wheel D will transmit to the screw D more or less of the shock which would ordinarily fall upon the teeth'of the detent. If the pitch of the grooves is increased, so that the sides of the grooves will lie more nearly at a right angle to the direction of motion of the teeth of the rack, the resultant of the shock brought upon the sides of these grooves by the teeth when the carriage is stopped will be greater in the direction of the axis of the shaft D than before, and, conversely, the resultant tending to rotate the wheel D will be less. Lessening the pitch of the groove on the wheel D will have the opposite effect, as is obvious. The wheel D thus acts as a sort of governor for the motion of the carriage, and by substituting wheels which have grooves of different pitch the friction on the dogs and the shock against them may be varied, as desired, While the extreme lightness of the parts and the absence of unnecessary friction are such that the speed of the carriage need not be substantially retarded. \Vhen the detent engages a tooth on the ratchet-wheel E, the wheel D will be at once stopped. The carriage will also be stopped, but with considerably less jar than would be the case if the detent directly engaged the teeth on the rack 13, because the projections from the carriage (in this embodiment the teeth on the rack) engage the inclined plane .formed by the sides of the grooves instead of a detent standing squarely across their path. In normal operation some of the teeth of the rack are preferably always in engagement with the grooves in the wheelD. Consequently the wheel will be rotated as soon as the carriage starts to move, and there will be no shock upon these parts when the carriage is released.

One great advantage of our construction as herein disclosed is that the teeth of the rack need not be as close together as is usual when the rack is directly engaged by the detent.

In our invention it is obvious that they may be as far apart as desired, providing the grooves of the wheel D are made to correspond. The teeth may therefore be as'thick as desired. Consequently the rack maybe made very strong.

It will be obvious that many modifications may be made in the construction herein disclosed, especially in the projection and abutting inclined-plane feature, without departing from the spirit of our invention.

IVhat we claim is- 1. In combination a movable carriage having a rack extending longitudinally across the same, means to exert a force upon said carriage to move it in one direction, a detent adapted to stop the same and prevent its movement in said direction and means between said carriage and detent comprising a light and spirally-grooved wheel adapted to be engaged and rotated by said rack to reduce the shock of said carriage upon said detent.

2. In combination a movable carriage having a rack extending longitudinally across the same, means to exert a force upon said carriage to move it in one direction, a detent adapted to stop the same and prevent its movement in said direction and means between said carriage and detent comprising a light and spirally-grooved wheel adapted to be engaged and rotated by said rack to reduce the shock of said carriage upon said detent, a ratchet-wheel rotated by the rotation of said spirally-grooved wheel and adapted to be engaged by said detent, said detent embracing a pair of relatively movable dogs.

Signed at Hartford, Connecticut, this 24th day of February, 1899.

JOHN M. FAIRFIELD. EDWIN II. DODGE. \Vitnesses to signature of John llLFairfield:

MINNIE ZINN, E. J. FAIRFIELD- \Vitnesses to signature of Edwin H. Dodge:

SYLVESTER BARBOUR, WM. \VARD. 

